(1) Field of Invention
The present invention relates to an oral pharmaceutical composition. In particular, the present invention relates to an oral pharmaceutical composition that acts to deliver drug throughout the small and large bowel.
(2) Prior Art
In the pharmaceutical arts it is often desirable to prevent the dissolution of drugs within the stomach. This may be to protect the stomach from the irritating effects of the drug or to protect the drug from being chemically degraded by the gastric juices of the stomach. This is routinely accomplished by applying enteric (gastric resistant) coating materials which allow drug dissolution to occur in the small intestine, the large intestine, or a portion of the small or large intestine. For example, in U.S. Pat. No. 4,780,318 an oral pharmaceutical composition is disclosed which comprises a core containing the active therapeutic compound and a carrier, a diffusion membrane, an outer layer and a flavored or colored layer applied outside. In that way the active compound begins to release only in the colon and not in the small bowel; however, this composition does not uniformly expose both bowels to the drug. Moreover, no current method exists which allows uniform and complete exposure of both the small and large intestine to drug while at the same time preventing dissolution of the drug in the stomach. No commercially available drug preparation is known to applicants that delivers drug at the low pH ranges that exists in the upper intestinal tract, and also in the lower intestinal tract and colon in the same dosage form.